An update is available for Windows 8.1. This update fixes an issue in which some third-party software solutions that use network intermediate (IM) filter drivers no longer work after you upgrade to Windows 8.1.
How to obtain this update
This update is applied automatically when you upgrade from Windows 8 to Windows 8.1.
To apply this update, you must have an internet connection while upgrading from Windows 8 to Windows 8.1.
For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:
824684 Description of the standard terminology that is used to describe Microsoft software updates